Drawing instrument



Feb. 9, 1932. K. D. HAMILTOQ ET AL DRAWING INSTRUMENT Filed April 7, 1928 Patented Feb. 9, 1932 unirsesrarss PATENT QFFICE KENNETH D. HAMIIlTON, 0F BRQGKTON, AND EDWARD HURST, 0F NEWTONVILLE,

. MASSACHUSETTS DRAWING INSTRUMENT Application filed April 7, 1928.

The present invention relates to drawing instruments and more particularly to that type of drawing instrument such as T-squares which, because of their necessary shape, are

5 awkward and inconvenient to carry about.

One of the objects of the present invention is to provide a drawing instrument, such as a T-square, which may be disjointed or collapsed into a compact form so that it may be carried about in any ordinary case or even inthe pocket of the user.

A further object of the present invention is to provide a collapsible or separable drawing instrument, such as a T-square, a portion of which is in the form of a box or case adapted to receive, whenthe instrument is c0llapsed or disjointed, the other portions of the instrument.

1 Still another object of the present invention is to device a T- quare having separable head and blade, the head being in the form of a box or case adapted to receive the blade, and preferably other drawing instruments and accessories.

With these objects in view the present in vention consists in the parts and combinat-ions of parts hereinafter described and more particularly defined in the claims.

The present invention is illustrated in connection with a knock-down or separable T- square, the T-square having a hollow head adapted to receive the two part blade but a collapsible triangle as well, besides providing space for the scale, pencil, etc. i a

In the drawings Fig. 1 shows intop plan view the T-square assembled, and Fig. 2 is a longitudinal, vertical section of the same on line 22 of Fig. 1 on somewhat enlarged scale; Fig. 3 is an. end elevation of the head of the T-square detached from the blade looking from the left in Fig. 1; 4 is a top plan View of the head of the T-square detached from the blade with the cover removed and with the disjointed blade and a folded triangle within the head; Fig. 5 is a vertical, longitudinal section or" the heat. of the T-square detached with the cover in place and with the disjointed blade and a folded triangle inside the head; Fig. 6 is a sectional Serial No. 268,149.

detail on line 6-6 of Fig. 1, and Fig. 7 is a sectional detail on line 77 of Fig. 1.

As shown in Fig. 1, the improved T-square comprises a head, indicated generally at 15, and a blade extending at right angles thereto, indicated generally by the reference character 17. The head 15 comprises a box-like structure having a bottom 19, the front and rear sides 21 and 23, and the ends 25, pressed or struck up from a single sheet or blank of thin metal such as aluminum. The rear wall 23 is extended slightly above the top of the front and end walls and forms a stop for the sliding cover 27 which consists of a flat piece of metal with its ends bent over to form grooves or guides to receive the laterally extending lips 29 upon the end walls 25. The cover maythus be slid along the open top of the box or head to close such box or to open it, as the case may be.

The blade, indicated generally by the reference character 17, comprises two sections 31 and 33, united by means of a connector strip or member 35. Each section of the blade which is of slightly shorter length than the inside length of the box-like head so that they may be received therein, is made with its side edges turned over as at 37 to form longitudinal grooves along each edge of the section. The connecting member is of proper dimension to fit snugly within such groove and by placing the sections end to end with the connecting member in such grooves and extending for one half of its length into each section, the parts are held firmly in align- {pent by the tightly fitting connecting mem- In order to avoid accidental displacement of the parts when in use, the connecting member is formed with a longitudinal slot 39 adjacent one edge and intermediate its ends, and a slight projection 41 is formed in the turned over margin of each section near their abutting ends and in position to project into the slot in the connecting member at each end thereof and thereby offer increased resistance to the separation of the blade sections.

The blade is secured in the head of the T- square in the following manner. Formed in the front wall 21 of the head is the slot or opening of the size and shape to receive with a tight fit the front end of the blade section 31. The opening thus has a straight flat bottom, rounded ends, widened portions at each end to receive the turned over margin of the blade section, and a narrow portion intermediate such ends for the single thickness of .metal at the middle of the blade. (See Fig. 6).

On the opposite or rear wall 23 of the head is formed a narrow straight slot 4.3 to receive the straight end of the blade section, the turned over marginsbeing cutback slightly at this point as indicated at 45 in Fig. 4, and their ends serving as abutmentsto engage the inner face of the rear wall of the head.

The blade may thus be inserted through the opening in the front wall 21 and passed through the box to enter the opening 48 in the rear wall. Fitting these openings snugly, the blade is held securely at right angles to the head.

In order to lock the blade in the head, the former is formedwith the spring tongue 47, shown in dotted outline in Figs. 1 and 6, and in longitudinal section in Fig. 2. This tongue is cut from the middle portion of the blade section and is sprung. upwardly sufiiciently i to have its free end raised slightly above the plane of the middle portion of the blade. hen the blade is being insertedin the head, the tongue is forced downwardly by the depending section of the front wall between the enlarged end portions oftheopening, permittingthe end of the'blade to enter the opening in the rear wall. Just as the ends ofthe turne over-margins at 45 abut the inner face of the rear wall, the end of the tongue clears the front wall 21 and springs upwardly in position to engage the inner face thereof, preventing withdrawal of the blade. The tongue will thus hold the blade securely in position in use without liability of loosening or separation of the parts. Toremove the blade it is only necessary to depress the tongue "to bring its end in line with the opening whereupon the'blade may be freely Withdrawn.

The manner of assembling and disjoining or collapsing the instruments has already been described and will not be here repeated. It will be observed, however, that all the '4 parts may be easily contained within the head of the T-square and that addltional space is provided for other instruments or drawing implements, such as pencils, erasers. etc. lVith the instruments in the head and the cover inplace,the user may carry his entire drawing equipment in his pocket with no more inconvenience than the ordinary folding two 'foot pocket rule. hen the triangle or T- square is needed, it requires but a few seconds to remove the parts from the box and assemble them, ready for use.

The parts being formed of sheet metal may be accurately and inexpensively manufactured, and where aluminum or some of its alloys are employed, the weight of the instruments will be negligible.

While the drawings have shown and the specification has described what is now considered the preferred form of the present invention, .it is to be understood that this is not limited thereto but may be embodied in other forms and arrangements within the scope thereof as defined in the accompanying claims.

Furthermore, where in the claims the term knock-down is employed, this is to be understood in its general sense and as defining a construction in which the parts are more or less permanently connected together, as by pivots, as well as a construction in which the parts may be entirely separated from one another.

lVhere, also,one member is defined as receiving another, this is to be taken in its broadest sense as covering a construction in which the one member embraces to a very substantial degree, but not necessarily completely, another member.

Having thus described the invention, what is claimed is:

1. A knock-down T-square comprising a head in the form of an elongated box and having blade receiving openings in its opposed walls, a blade, two separable sections comprising elongated flat members with overhanging lips at their margins, a connection member overlying the abutting ends of the sections and with its longitudinal marginal portions received beneath said lips to hold the sections in alignment, said connecting member being provided with a recess and the sections with projections cooperating therewith to prevent the accidental separation of said sections.

2. A knock-down T-square comprising a head in the form of an elongated box having front and rear walls, a blade, the front and rear walls of the head being formed with blade receiving openings to hold the blade at rightangles to the head,- the blade being formed with a shoulder adjacent its end to limit the movement of the blade in one direction and with a spring tongue to limit the movement of the blade in the other direction relatively to the head, said tongue being adapted to be pressed by the operator to permit removal of the blade from the head.

In testimony whereof we have signed our names to this specification.

KENNETH D. HAMILTON.

EDWARD HURST. 

